Cell phones helping cell phones

Now, I’m leery of the phrase “paradigm shift,” which is often applied to incremental, evolutionary improvements. But perhaps one is upon us in the cell-phone industry—if an idea presented by Mike Farmwald at the MTT-S International Microwave Symposium gains traction.

Farmwald, director of Skymoon Ventures, described his idea at a June 16 keynote address titled “Sharing is good, or how to build a truly open network.” The crux of the issue is that today, cell phones communicate only with cell towers (with the exception of WiFi-enabled phones, which can communicate with WiFi access points). Farmwald said he envisioned a future in which communication moves from a cell-phone to tower model to a cell-phone to cell-phone to tower to access point model.

If cell phones could cooperate using a side channel, one phone with a poor connection (because of in-building loss, for example) could possibly get help from a phone near a window 20 feet away that has better connectivity, he said, adding that there would be huge advantages in terms of SNR and other performance parameters. Two phones cooperating would experience a 3-dB improvement. An AC-operated station without a user interface and located near a window could yield a 15-dB improvement. Further, he said, such a system could significantly reduce transmit power.

The concept should be a win for all concerned—consumers would experience better connections, fewer dropped calls, and longer battery life, and carriers could double their bits/second/hertz performance with no changes to their infrastructure. Even better for carriers, customers such as large businesses would take on some of the infrastructure expenses, installing, for instance, the stations that connect side-channel links (which would use spectrum not owned by the carriers) from cell-phones the carriers’ base stations.

It’s a simple and elegant idea (and Farmwald acknowledged that ad hoc phone sharing schemes have been presented before). But if the technology is easy to understand (if not necessarily easy to implement), the politics can be more complicated. Wireless carries, Farmwald said, would need to make decision to drive a new generation of cell phones with side-channel capability (Farmwald mentioned 1.9-GHz DECT and WiFi), and carriers would need to adopt a universal standard for communication and authentication. (Authentication would be required to handle billing issues, for example. If my phone makes use of your phone’s better access to a cell tower, I’m the one that need to be billed.)

There are several impediments to his approach, he said—getting a critical mass of sharing devices being one. Another is that the scheme would help smaller carriers catch up in coverage with their larger competitors, perhaps discouraging larger carriers from participating.

But reiterated the advantages—twice the bits/second/hertz, lower power, and fewer dropped calls, and he added that non-phone applications, like M2M (machine-to-machine) communications, could increase data revenues for carriers. In addition, he said, every sharing phone would become a world phone, and every sharing phone could immediately take advantage of new spectrum and network capabilities—such as LTE.